1. Field of the Invention
The present invention relates generally to electrical current switches, and more particularly to a switch for gradually reducing a flow of current through the switch before disconnecting two conductors so as to avoid inducing a current arc across the switch when disconnecting the conductors.
2. Discussion of the Prior Art
Electrical current flowing through a conductor in a circuit including an inductive load such as a power supply transformer induces an electrical field which tends to maintain the flow of current through the conductor. The greater the current flow, the stronger the electrical field. When points such as switch contacts in the conductor are being disconnected, such an electrical field will briefly tend to induce a voltage surge causing an arc across the opening between the points being disconnected. Such current arcs can weld together switch contact points or damage other components in the circuit. This problem of arcing may be handled by deactivating all affected components before "powering down" the power supply in a circuit. Alternatively, current arcs may be handld by a surge suppressing device incorporated into a circuit. A variable resistance device (such as a rheostat) can be used in a circuit to gradually reduce the current flow and accompanying tendency to art. However, conventional variable resistances are deficient for this function because surge suppressing devices must be scaled to sizes capable of handling particular applications, and are often undesirably costly and inconvenient. Furthermore, conventional variable resistances would also require switches.
Thus, there is a need for a means to gradually reduce the flow of current between two conductors to reduce the induction of an electrical field which would tend to arc current across the opening between points in the two conductors being disconnected.